Gold or gold alloy plating has been widely utilized in recent years in electronic equipment and electronic components, especially to protect the connection terminals of electronic components and the like, because of its solder wetting spreadability, electrical properties, corrosion resistance, wear resistance, and the like. Gold plating is also used as surface treatment of the electrode terminals of semiconductor elements and as surface treatment of electronic components such as connectors that connect electronic equipment. The gold plating film used as a surface treatment must have solder wetting spreadability, corrosion resistance, wear resistance, and electrical conductivity given the utilization characteristics of connectors that connect electronic equipment.
However, since gold is expensive, the amount used must also be kept down. Nonetheless, when the gold plating film is thinned to keep down the amount of gold used, pinholes in the gold plating film increase. These pinholes cause problems such as corrosion of the substrate of the gold plating film, raise the contact resistance, and lower the reliability due to the penetration of water, chlorides, and other such corrosive substances.
Treatment to prevent corrosion called sealing is carried out to solve this problem. For example, JP Kokai 2003-129257 describes a water-based sealing agent containing an inhibitor selected from benzotriazole compounds, mercaptobenzothiazole compounds, or triazinethiol compounds, a surfactant, and an amine compound. JP Kokai 2000-17483 describes a method of bringing a substrate provided with a gold-containing metal film on the surface into contact with an aqueous solution containing benzothiazole or a derivative thereof and forming a anticorrosive film on the substrate surface. JP Kokai 2000-15743 describes a plating material obtained by forming an organic material bonding layer consisting of an organic compound containing a thiol group (—SH) on a gold or gold alloy plating layer and also forming a lubricating layer on top.
These methods, however, do not have an adequate anticorrosive effect, and a surface treatment agent having a higher anticorrosive effect is demanded.